Astronomical dating of Quaternary strata in the South Yellow Sea and its indication for paleoclimatic evolution

Abstract

The continental shelf has experienced high-frequency transgression-regression cycles during the Quaternary, and its sediments have stored significant information on sea-level changes, climate fluctuations and regional tectonic activities. Due to the lack of extended core records and high-resolution stratigraphic chronology, the strata correlation between continental and marine basin since the Quaternary still has considerable limitations. Here, we present a high-resolution grain size and geochemical study of core CSDP-1 (~3.5 Ma) recovered from the western South Yellow Sea (SYS), China. Two sensitive components were extracted from sediments, and their contents can be used to reflect the paleo-hydrodynamic intensity and reconstruct paleoclimate change. A comprehensive analysis including lithologic characteristics of sediments and seismic data interpretation, shows that the stratum deposition at the borehole's location is relatively continuous at the orbital time-scale. The results of spectral analysis, show that the fine sensitive component it records the periodic change information of the Earth's orbital parameters (~400-, 100-, 40-, and 20-kyr), and the astronomical chronology was established successfully. The variations of sensitive components in the sediments reveals that the SYS paleoclimate has undergone four periods since the Quaternary: cold conditions during 2.58–2.49 Ma and 1.88–0.83 Ma, warm and humid conditions during 2.49–1.88 Ma and 0.83–0 Ma. Moreover, the stratum in the SYS shelf records the Middle Pleistocene climate transition (MPT). It is inferred that the MPT in the SYS is mainly manifested by the enhancement of the 100-kyr period related to the synchronous forcing of the ~400-kyr eccentricity.